The aim of the study proposed herein is to determine whether mood will change in depressed patients during simultaneous serotonin and catecholamine depletions. The specific objective of this study is to assess the effect of simultaneously depleting both indoleamines (5-HT) and catecholamines (NE and DA) on mood in depressed subjects. The tested hypothesis will be: Mood changes associated with simultaneous cathecholamine depletion (via AMPT admininstration) and indoleamine depletion (via acute dietary tryptophan depletion) will be greater in depressed subjects than nondepressed subjects.